Solute partitioning in micelles: combining molecular dynamics simulations, COSMOmic, and experiments

Journal
The journal of physical chemistry B  
Volume
121
Issue
23
Start Page
5794
End Page
5809
Citation
Journal of Physical Chemistry B 23 (121): 5794-5809 (2017-06-15)
Publisher DOI
10.1021/acs.jpcb.7b03147
Scopus ID
2-s2.0-85021681899
Publisher
Soc.
The partition equilibria of solutes between micelles and an aqueous phase is a key factor in many applications. Depending on the task, many micelle-solute combinations are possible. Therefore, theoretical methods to predict the partition behavior in micellar systems are needed. Here, two predictive methods are evaluated and compared. First, it is shown how molecular dynamics simulations (MD) with the umbrella sampling method can be used to calculate free energy profiles in micellar systems. The second applied method is an extension of the COSMO-RS theory to anisotropic systems termed COSMOmic. Both methods are compared by means of free energy profiles and experimental micelle/water partition coefficients. A particular focus is on the partitioning of ionized solutes. As experimental data for partitioning in micelles especially for charged solutes is rare, partition coefficients were also determined experimentally. To get a general understanding of micelles examples of all micelle classes (classified by headgroup charge) are studied: nonionic Triton X-114 (TX114), zwitterionic miltefosine (HePC), anionic sodium dodecyl sulfate (SDS), and cationic cetyltrimethylammonium bromid (CTAB). The free energy profiles of neutral solutes obtained from MD simulations and COSMOmic are in an overall good agreement, and partition coefficients from both methods are in good agreement with experimental data. Depending on the system, the results for charged solutes show some deviations between the methods and experimental data.
DDC Class
600: Technik
620: Ingenieurwissenschaften
More Funding Information
Support of the German Academic Exchange Service (DAAD) and from the Hamburg University of Technology research center “Integrated Biotechnology and Process Engineering”. Computational resources have been provided by The North-German Supercomputing Alliance (HLRN).